&optionalx → implementation-dependent
room prints, to standard output, information about the state of internal storage and its management. This might include descriptions of the amount of memory in use and the degree of memory compaction, possibly broken down by internal data type if that is appropriate. The nature and format of the printed information is implementation-dependent. The intent is to provide information that a programmer might use to tune a program for a particular implementation.
(room :default) prints out an intermediate amount of information that is likely to be useful.
Output to standard output.